The stakes are high: Dow Corning was bankrupted by lawsuits in the 1990s alleging its implants caused a variety of illnesses even though the Institute of Medicine eventually concluded that they don't.

There is, of course, no love lost between Allergan and the FDA. The company sued the agency in 2009 (and later capitulated), claiming the feds were infringing on its First Amendment rights to promote Botox for headaches even though it did not have FDA approval to do so. Even so, Allergan's reaction to the FDA cancer warning sharply contradicts the federal agency's statement in a way that is rare for a drug company. Because pharmaceutical firms are dependent on the FDA to approve new products, they generally take a deferential approach to it in public. Not Allergan.

... the FDA believes that women with breast implants may have a very small but increased risk of developing this disease in the scar capsule adjacent to the implant. Based on available information, it is not possible to confirm with statistical certainty that breast implants cause ALCL.

The FDA called ALCL "a very rare type of cancer." Allergan, in response, denied that ALCL is "breast cancer":

Reports of ALCL in patients with breast implants are extremely rare and are not to be mistaken for breast cancer.

(Re-)Do the Math
Allergan even disputed the FDA's case report numbers. The FDA said it had "about 60" cases; Allergan claimed:

... only 34 cases of ALCL have been identified and reported in peer-reviewed literature over nearly 15 years, since 1997.

The FDA's statement said that in general the chance of getting ALCL in breast tissue is 3 in 100 million, but that it had found 60 cases in women with implants. There are 5-10 million women worldwide who have implants, so if the FDA's numbers are correct then there's a 1 in 166,666 chance of getting ALCL if you have implants -- a far higher risk than 3 in 100 million (or 1 in 33.3 million, if you want comparable numbers) for the general population. Allergan, however, pooh-poohed the risk:

A woman is more likely to be struck by lightning than get this condition.